The objective of this project is to elucidate the molecular mechanisms by which interferons (IFN) regulate the expression of a number of specific genes in human fibroblasts. It has been demonstrated that IFN treatment induces the synthesis of several new proteins in these cells and induction of these proteins parallels induction of the antiviral state. Our preliminary results indicate that synthesis of these proteins in IFN-treated cells is regulated both at transcriptional level and at translational level. Moreover, the nature of this regulation is different in IFN-alphaand IFN-gamma-treated cells. In this project we will isolate and characterize cDNA clones corresponding to IFN-induced mRNAs. We will use those cloned cDNAs as hybridization probes for identifying different IFN-inducible mRNAs and for studying the regulation of synthesis and turnover of these mRNAs. We also will use the cDNA clones to screen a human genomic library for isolation of the corresponding genes. Once the genomic clones are isolated they will be characterized by restriction enzyme-mapping. Finally, we will introduce the isolated IFN-inducible genes into heterologous cells and examine their expression. This project will provide us with reagents and assay systems necessary for achieving our long-term objectives of understanding the nature of the molecular signals that regulate the expression of these IFN-inducible genes and of correlating the induction of a specific gene with a specific IFN-inducible biological phenotype. Information obtained from this system will also be valuable for understanding the modes of regulation of eucaryotic gene expression in general.